Exhaust Heat Recovery System of Vehicle and Method Thereof

ABSTRACT

An exhaust heat recovery device may include a radiator disposed at a main line and through which hot coolant circulates, an exhaust heat exchanger transferring exhaust heat of an engine to coolant, a first valve selectively circulating the coolant to the main line or a bypass line, a water pump connected to the first valve and circulating the coolant, a coolant temperature sensor detecting temperature of the coolant, a second valve connected to the water pump and disposed at a distributing line to distribute the coolant supplied by the water pump to the engine and the exhaust heat exchanger, and a control portion that controls the first and second valves depending on the temperature of the coolant so as to adjust coolant amount circulating in the engine and the exhaust heat exchanger and coolant amount circulating in the radiator and the bypass line.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2009-0118730 filed in the Korean Intellectual Property Office on Dec. 2, 2009, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exhaust heat recovery device of a vehicle. More particularly, the present invention relates to an exhaust heat recovery device of a vehicle that recovers heat of exhaust gas to decrease fuel consumption, and a method thereof.

2. Description of Related Art

In general, vehicle makers are researching ways to decrease exhaust gas and fuel consumption.

When a catalyst loading amount is increased and an EGR cooler capacity becomes larger so as to satisfy exhaust gas regulations, the manufacturing cost of a vehicle is also increased.

A variable water pump prevents unnecessary cooling such that warm-up time of an engine is reduced and fuel consumption is reduced.

Further, an exhaust heat recovery device is being developed and applied so as to recover lost exhaust gas energy, wherein the exhaust heat recovery device is disposed at a downstream side of the exhaust gas catalyst to transfer heat of the exhaust gas to the coolant such that the warm-up time of the engine is reduced.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention are directed to provide an exhaust heat recovery device of a vehicle having advantages of reducing fuel consumption and improving quality of exhaust gas by actively varying a coolant amount circulating in an exhaust heat exchanger and an engine according to temperature of a coolant during operation of an engine.

That is, a small amount of coolant circulates in the engine and a large amount of coolant circulates in the exhaust heat exchanger so as to improve energy efficiency in an early stage of cold starting.

In an aspect of the present invention, the exhaust heat recovery device of a vehicle, may include a radiator that is disposed at a main line and through which hot coolant circulates so as to radiate heat thereof; an exhaust heat exchanger that transfers exhaust heat of an engine to coolant; a first valve that selectively circulates the coolant absorbing combustion heat of the engine to the main line or a bypass line; a water pump connected to the first valve and circulating the coolant; a coolant temperature sensor detecting temperature of the coolant; a second valve that is connected to the water pump and is disposed at a distributing line to distribute the coolant supplied by the water pump to the engine and the exhaust heat exchanger; and a control portion that controls the first and second valves depending on the temperature of the coolant detected by the coolant temperature sensor so as to adjust coolant amount circulating in the engine and the exhaust heat exchanger and coolant amount circulating in the radiator and the bypass line.

The exhaust heat exchanger may be disposed at a downstream side of an exhaust catalyst.

The control portion may control the second valve such that the coolant amount circulating in the exhaust heat exchanger becomes larger than that of the coolant circulating in the engine when the temperature of the coolant is less than a first predetermined value, wherein the control portion controls the first valve such that circulation of the coolant in the radiator is closed and circulation of the coolant in the bypass line is opened.

The control portion may control the second valve such that the coolant amount circulating in the exhaust heat exchanger is minimized or closed and the coolant amount circulating in the engine is maximized when the coolant temperature is higher than a second predetermined value, wherein the control portion controls the first valve such that circulation of the coolant in the radiator is opened and circulation of the coolant in the bypass line is closed.

An auxiliary device may be connected to the bypass line.

In another aspect of the present invention, the exhaust heat recovery method of a vehicle, may include detecting a temperature of a coolant and comparing the detected temperature with a first predetermined temperature value; adjusting a passage of the coolant such that the coolant amount circulating in an exhaust heat exchanger is larger than that of the coolant circulating in an engine when the temperature of the coolant is less than the first predetermined temperature value; and controlling the coolant such that the coolant amount circulating in the engine is larger than that of the coolant circulating the exhaust heat exchanger when the temperature of the coolant is higher than a second predetermined temperature value, wherein a second valve may be disposed at a distributing line connected to a water pump to distribute the coolant to the engine and the exhaust heat exchanger according to the temperature of the coolant.

The exhaust heat recovery method may further include circulating the coolant to a bypass line when the detected temperature is lower than the first predetermined temperature value; and circulating the coolant to a radiator when the detected temperature is higher than the second predetermined temperature value, wherein the first predetermined temperature value is lower than the second predetermined temperature value, wherein a first valve may be connected to a water pump and selectively regulates circulation of the coolant to the bypass line and the radiator.

In the present invention as stated above, the coolant is actively controlled in an early stage of starting of the engine so as to shorten a warm-up time of the engine such that fuel consumption is reduced and exhaust gas is stabilized.

In the present invention, stable exhaust gas can be secured without adding a catalyst, the temperature of engine oil can be quickly raised, oil friction is rapidly decreased, and abrasion of components is minimized such that durability thereof is improved.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematically showing an exemplary exhaust heat recovery device of a vehicle according to the present invention.

FIG. 2 is a flowchart showing an exemplary exhaust heat recovery procedure in a vehicle according to the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration.

FIG. 1 schematically shows an exhaust heat recovery device of a vehicle according to an exemplary embodiment of the present invention exemplary embodiment.

The present invention includes an engine 10, a radiator 20, an exhaust heat exchanger 30, an auxiliary device 40, a water pump 50, a coolant temperature sensor 60, a control portion 70, a first valve 80, and a second valve 90.

The radiator 20 is disposed at a main line 22 to radiate combustion heat when the engine 10 is sufficiently warm.

The exhaust heat exchanger 30 is disposed at a downstream side of a catalyst, and a coolant circulates therethrough to transfer exhaust heat of the engine 10 to the coolant such that the warm-up time of the engine 10 is reduced.

The auxiliary device 40 includes a heater through which the coolant circulates for heating the interior of the vehicle.

The water pump 50 is variably operated, and particularly the water pump 50 is not operated if the coolant temperature is less than a predetermined value, and while the engine 10 is operating, warm up time of the engine 10 is reduced by preventing unnecessary cooling and fuel consumption is reduced by decreasing friction resistance of lubricating oil.

The temperature sensor 60 detects the temperature of the circulating coolant and transfers a detected signal to the control portion 70.

The control portion 70 controls the water pump 50, the first valve 80, and the second valve 90 according to the temperature of the coolant detected by the temperature sensor 60 while the engine 10 is on, such that the warm-up time of the engine 10 is reduced.

The first valve 80 is disposed at a circulation line of the coolant to determine a circulation passage of the coolant according to control of the control portion 80.

For example, in a normal driving condition in which the engine 10 is warmed up completely, the coolant circulates through the radiator 20, and in an abnormal driving condition in which the engine 10 is not warmed up, the coolant does not circulate through the radiator 20 but flows through a bypass line 42.

In this process, the coolant can circulate through the auxiliary device 40 depending on driving conditions.

The second valve 90 as an electric control valve is disposed at distributing line 33 of the water pump 50, the engine 10, and the exhaust heat exchanger 30 to adjust the route of the coolant circulated by the water pump 50 according to control of the control portion 70.

For example, in a condition in which the engine 10 is not sufficiently warm or the coolant temperature is less than a predetermined temperature, the coolant amount circulating in the engine 10 becomes less than the coolant amount circulating in the exhaust heat exchanger 30 according to control of the control portion 70 to induce a quick increment of the coolant temperature.

Also, in a condition in which the engine 10 is sufficiently warm or the coolant temperature is higher than a predetermined temperature, the coolant amount circulating in the engine 10 is maximized and the coolant amount circulating in the exhaust heat exchanger 30 is minimized or closed according to control of the control portion 70.

The first valve 80 and the second valve 90 are general thermostats or electronic control valves operated by control of the control portion 70.

Referring to FIG. 2, operation of the present invention including the functions as stated above is explained as follows.

FIG. 2 is a flowchart showing an exhaust heat recovery procedure in a vehicle according to an exemplary embodiment of the present invention.

In a condition in which the engine 10 is off (S101), if starting of the engine 10 is detected (S102), the control portion detects the coolant temperature provided by the coolant temperature sensor 60 (S103) and determines whether the coolant temperature is less than a predetermined temperature (A° C.) as a cold starting condition (S104).

If the coolant temperature is higher than the predetermined temperature (A° C.) in S104, the first valve 80 performs general coolant circulation control according to the coolant temperature (S105) such that the coolant circulates in the radiator 20.

However, if the coolant temperature is less than the predetermined temperature (A° C.) in S104, the control portion determines that the engine is in a cold condition (S106) and controls the first valve 80 (S107) such that the coolant does not circulate in the radiator 20 but circulates through the bypass line 42 (S108).

Further, the control portion 70 operates the water pump 50 to circulate the coolant (S109), and simultaneously controls the second valve 90 (S110) such that the coolant amount circulating in the engine 10 becomes lesser than the coolant amount circulating in the exhaust heat exchanger 30 to induce a quick increment of the coolant temperature (S111).

Accordingly, the coolant temperature is raised by the combustion heat of the engine and the exhaust heat exchanger 30, and the control portion then determines whether the coolant temperature is higher than a predetermined temperature (B° C.) as a criterion for judging a warm-up condition (S112).

If the coolant temperature is higher than the predetermined temperature (B° C.) as a criterion for judging a warm-up condition in S112, the control portion 70 determines that the engine 10 is warm (S113), and controls the first valve 80 S114 to circulate the coolant through the radiator 20 (S115).

At the same time, the control portion controls the second valve 90 (S116) such that the coolant amount circulating in the exhaust heat exchanger 30 is minimized or closed and the coolant amount circulating in the engine 10 is maximized (S117).

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. An exhaust heat recovery device of a vehicle, comprising: a radiator that is disposed at a main line and through which hot coolant circulates so as to radiate heat thereof; an exhaust heat exchanger that transfers exhaust heat of an engine to coolant; a first valve that selectively circulates the coolant absorbing combustion heat of the engine to the main line or a bypass line; a water pump connected to the first valve and circulating the coolant; a coolant temperature sensor detecting temperature of the coolant; a second valve that is connected to the water pump and is disposed at a distributing line to distribute the coolant supplied by the water pump to the engine and the exhaust heat exchanger; and a control portion that controls the first and second valves depending on the temperature of the coolant detected by the coolant temperature sensor so as to adjust coolant amount circulating in the engine and the exhaust heat exchanger and coolant amount circulating in the radiator and the bypass line.
 2. The exhaust heat recovery device of claim 1, wherein the exhaust heat exchanger is disposed at a downstream side of an exhaust catalyst.
 3. The exhaust heat recovery device of claim 1, wherein the control portion controls the second valve such that the coolant amount circulating in the exhaust heat exchanger becomes larger than that of the coolant circulating in the engine when the temperature of the coolant is less than a first predetermined value.
 4. The exhaust heat recovery device of claim 3, wherein the control portion controls the first valve such that circulation of the coolant in the radiator is closed and circulation of the coolant in the bypass line is opened.
 5. The exhaust heat recovery device of claim 1, wherein the control portion controls the second valve such that the coolant amount circulating in the exhaust heat exchanger is minimized or closed and the coolant amount circulating in the engine is maximized when the coolant temperature is higher than a second predetermined value.
 6. The exhaust heat recovery device of claim 5, wherein the control portion controls the first valve such that circulation of the coolant in the radiator is opened and circulation of the coolant in the bypass line is closed.
 7. The exhaust heat recovery device of claim 1, wherein an auxiliary device is connected to the bypass line.
 8. An exhaust heat recovery method of a vehicle, comprising: detecting a temperature of a coolant and comparing the detected temperature with a first predetermined temperature value; adjusting a passage of the coolant such that the coolant amount circulating in an exhaust heat exchanger is larger than that of the coolant circulating in an engine when the temperature of the coolant is less than the first predetermined temperature value; and controlling the coolant such that the coolant amount circulating in the engine is larger than that of the coolant circulating the exhaust heat exchanger when the temperature of the coolant is higher than a second predetermined temperature value.
 9. The exhaust heat recovery method of claim 8, further comprising a second valve that is disposed at a distributing line connected to a water pump to distribute the coolant to the engine and the exhaust heat exchanger according to the temperature of the coolant.
 10. The exhaust heat recovery method of claim 8, further comprising: circulating the coolant to a bypass line when the detected temperature is lower than the first predetermined temperature value; and circulating the coolant to a radiator when the detected temperature is higher than the second predetermined temperature value, wherein the first predetermined temperature value is lower than the second predetermined temperature value.
 11. The exhaust heat recovery method of claim 10, further comprising a first valve connected to a water pump and selectively regulates circulation of the coolant to the bypass line and the radiator. 